In the midst of the busy semester here at school, my fiancee's laptop, running Windows XP SP2, picked up some friends - adware, trojans, etc. It was a pretty nasty sight. I worked on it for at least two hours every couple of days, wiping it clean, doing my best to lock it down, and so on. Avast! and Ad-Aware had their limits it seemed, for only a day or so after I cleaned it, pop-ups and weird stuff would show up again. She was getting sick of it. I was getting sick of cleaning it, so I suggested, offhand, installing a different operating system that is a bit more impervious to those nasties. To my surprise, she agreed.